This invention relates to a two-wheeled vehicle such as a bicycle, motorcycle and the like and more particularly to a two-wheeled vehicle with a hydraulic transmission.
A chain transmission system has been widely used for transmission of two-wheeled vehicles. It has been practically used to shift a chain from one to the other of multiple stage sprockets to change speeds of a two-wheeled vehicle.
Speed change means other than the above prior art have been disclosed, for example, in Japanese Patent Application Publication No. 1,722/59 and Japanese Laid-open Patent Application No. 54-93,754.
In the above chain shifting system, although stepwise speed change is effected, stepless speed change is impossible. Moreover, the speed change devices disclosed in the Japanese Patent Application Publication No. 1,722/59 and the Japanese Laid-open Patent Application No. 54-93,754 are theoretically capable of performing a stepless speed change. However, these devices have not been practically used owing to pulsation and noise produced in operation and difficulty to obtain sufficient transmission ratio.
Recently, as cross-country cycling and mountain cycling have become popular, bicycles as sports bicycles suitable for bad roads have been expected. Although it has been known that front wheel drive is very effective on bad road, it is impossible to realize the front wheel drive in a chain-drive bicycle because a front wheel always changes its direction with handle bars.